This invention relates to storage systems, and in particular to techniques of assuring data integrity in such systems.
Large organizations throughout the world now are involved in millions of electronic transactions which include enormous amounts of text, video, graphical and audio information. This information is being categorized, stored, accessed, and transferred every day. The volume of such information continues to increase. One technique for managing such massive amounts of information is to use storage systems. Conventional storage systems include large numbers of disk drives operating under various control mechanisms which record, mirror, remotely backup, and reproduce this data. This rapidly growing amount of data requires most companies to manage the data carefully with their information technology systems.
An increasingly important aspect in the management of such data is the need to preserve it and to later establish that the data has not been altered. For example, a common goal in the management of data is now to preserve the data on a certain volume at a certain point in time for a certain period of time. For example, in the United States, Securities and Exchange Commission Rule 17a-4 requires certain institutions to preserve communication information, such as e-mail, voice mail, and various documents, for a specified amount of time. To date such preservation of data has often taken the form of copying the data to various media, and associating with that media certain precautions to assure that the media is not changed between the time when the data was originally stored and some later time. In one such example, data is backed up using tape drives and the tapes securely maintained to assure that they have not been altered since being originally written. Unfortunately, such mechanisms are cumbersome, inefficient, and difficult to implement. The various measures often substantially increase the cost of preserving the data.
Accordingly, it would be desirable to have a more efficient and effective mechanism for assuring the integrity of stored data, but without the inconvenience of prior systems, such as backup systems.